Substrates, especially sensitive substrates, have to be handled isolated during the production process so that the substrates are not subjected to contamination, moisture, oxygen, other gases or other conditions deteriorating the sensitive substrates. Therefore these sensitive substrates have to be handled such that they are subjected as little as possible to deteriorating conditions. The sensitive substrate may be for example moisture, water vapour and oxygen sensitive organic light-emitting diodes (OLEDs).
When the sensitive substrates are coated or processed in a coating apparatus by subjecting the substrates at least partly to surface reactions of at least a first precursor and a second precursor, the sensitive substrates have to be loaded to the coating apparatus such that the substrates are subjected to deteriorating conditions as little as possible. The substrates may be processed by subjecting the substrates to surface reactions of at least the first and second precursor according to the principles of atomic layer deposition (ALD).
Conventionally the sensitive substrates are loaded to a shipment box or bag in the manufacturing line. The shipment box usually comprises an inert gas atmosphere, such as nitrogen atmosphere, for keeping the substrates isolated from the deteriorating conditions. The substrates are loaded into the shipment box in an inert gas atmosphere and the shipment box is then transported to processing site. In the processing site the shipment box is unloaded in a glove box having an inert gas atmosphere. From the glove box the substrates are quickly transferred and loaded to the coating apparatus in the ambient atmosphere. In this context, ambient atmosphere means atmosphere present in any operation environment of an ALD reactor, ranging from a factory-like production facility with a high amount of airborne impurities and/or uncontrolled humidity to a special-purpose environment such as a cleanroom with an extremely low (but usually nonzero) amount of impurities and potentially carefully regulated humidity. Therefore the substrates are subjected to ambient atmosphere and moisture during loading to the coating apparatus. In the coating apparatus the substrates are flushed with inert gas flow. However, the quality of the sensitive substrates is compromised as the substrates are subjected to ambient atmosphere and moisture during loading to the coating apparatus.
This prior art problem is solved by integrating the glove box to the coating apparatus. This arrangement allows inert handling of the substrates from the shipment box into the coating apparatus such that the substrates are not subjected to ambient atmosphere or other deteriorating conditions. Thus the substrates may be unloaded from the shipment box in the glove box and loaded into the coating apparatus via a load-lock having a separate vacuum chamber equipped with a gate valve for connecting the glove box to the coating apparatus.
The problem of the prior art arrangement in which the glove box is integrated to the coating apparatus is that the glove box is subjected to elevated temperatures, process gases and possible impurities during loading and unloading of the coating apparatus. Usually cross-contamination of the coating apparatus and the glove box is likely to happen. To minimize the contamination the operating temperature of the coating apparatus must be limited to about 50° C. Furthermore, the integration of the glove box and the coating apparatus has to be permanent for efficient purification of the inert gas glove box. The permanent integration limits the usability of both the coating apparatus and the glove box to a specific planned application, which is undesirable as the coating apparatus may not process different kind of substrates.